Don't forget that many of the areas that we're talking about are public areas: that means that Public funds built them, or that they are for public use. That includes National Parks, Forest Service roads and DNR areas.
Charging a fee for them, other than that of the Forest Service Permit, would not be in keeping with the spirit of the areas that most of us wheel in.
As for Trash - my father always told us to leave the place cleaner than when you found it. Sadly, many times I go out I don't have enough trash bags for the spent shotgun shells, brass and beer cans that I find when I try to stop somewhere with my kids to enjoy a peaceful stream or a nice meadow. That really, really chaps my ass more than I can say. As much as I'd like to take a few minutes to clean all that up, the last time I tried my kids were picking up dud shells whose primers had been struck... That was the end of the cleanup for me.
Drinking on the trails.. Everyone I've ever had to help off a rock or get unwedged from a tree was throwing them back and reeked of booze. No offense to anyone here, but that's the kind of crap that I just can't stand.
Bypasses - not at the expense of the trail system.
Gates - sure, except that you'll have to armor them against Human Squirrels: how many gates can you build and then not supervise against portable blow torches or alcohol fueled morons with shotgun slugs?
Fees or trail ratings based on tire size?? Elitist much, folks? Again - public roads! Granted, they are not always accessible to stock rides, but let's not forget who is paying the bulk of the building and maintenance fees, here. Most of the backlogs in maintenance at our national parks or forest service areas are needed to maintain walking trails, bridges and the like. If we don't pay for the materials and volunteer our time, then our trails will vanish due to neglect and funds that need to be diverted elsewhere for the greater common good.
Yes - many of you are hitting the nail on the head. It's a few bad apples that spoil the bunch. Know what? Take pictures, get license plates TURN THEM IN - keep the idiots off the trails who are doing the most damage and causing the drama which makes legal, law abiding, "tread lightly" types look bad because we get lumped in!
Sorry if I'm ranting - nothing personal against anyone here...